MOSCOW (Reuters) - The Russian and U.S. chiefs of general staff agreed on Saturday to fully resume the implementation of a joint memorandum on preventing mid-air incidents over Syria, Russian news agencies quoted the Russian Defence Ministry as saying.

Russian General Valery Gerasimov and General Joseph Dunford of the United States discussed in a phone call the Syria de-escalation zones and agreed to continue working on additional measures aimed to avoid clashes in Syria.

The aircraft safety memorandum was signed in October 2015 after Russia began bombing targets in Syria to support Syrian government forces in their fight against Islamic State and other armed groups.

In Washington, a Pentagon spokesman said in a statement that Dunford and Gerasimov "talked about the recent Astana agreement and affirmed their commitment to de-conflicting operations in Syria. Both also agreed to maintain regular contact."

An agreement reached at peace talks in Astana, Kazakhstan, and backed by Russia, Iran and Turkey, calls for "de-escalation zones" in major areas of conflict between Syrian government forces and rebel groups.